Essential Oils

ENGINEERINGAND SCIENCE May 1961, Volume XXIV, No. 8 Oils were used abund- antly in daily life in ancient times. In this early Egyptian painting from the tomb of Senejem, a son presents a libation of fragrant oil to Senejem and his wife. ESSENTIAL OILS More than a million different species of plants and known organisms ( less than half of one percent ) have animals have already been described by taxonomists, received little more attention than a label from tax- and new species are discovered every day. Even in onomists, it is clear that much work still has to be densely populated areas it is still possible to discover done. Nevertheless, the study of natural products has some new species, as George MacGinitie, Caltech's played an important role in the development of or- emeritus professor of biology, proved in our time by ganic chemistry, and has given us products of great digging up a nearly-one-foot-long animal, the urechis commercial and medical importance. caupo, on a California beach. The present revival of interest in these compounds has the chemist done with this wealth of from natural products continues to give evidence of m ? In handbooks on chemistry we find listings the astounding synthetic abilities of living organisms. of fat, carbohydrate, and protein content of many Through a revolution in analytical methods, as well anisms, and in addition some 10,000 miscellaneous as progress made in biochemistry, new research ave- compounds which are found in individual species. nues have been opened for such classical problems as hen we realize that only a small fraction of all those of alkaloids and pigments. These compounds no May, 1961 The study of essential oils has had an exciting Now, with improved analytical techniques, it has an equally exciting future. longer stand by themselves as freaks of nature, but position is also given for a perfume (a name used in have become expressions of general metabolic proc- the old original sense, meaning that which is pro- esses. duced by burning). In many places it mentions the The same is true of another group of natural prod- use of spices and odoriferous oleoresins such as ucts known as essential oils. This name is a very old myrrh, cinnamon, and labdanum. one and refers to the alchemists' idea of the most Caravans from India and China brought many of sublime extractive, the Quinia Essentia. This material these products to Egypt. As the Bible tells us in was, in general, the active ingredient of pharmacol- Genesis 37:25, after Joseph was cast into a pit by his ogically important drugs. Later the name was applied brothers : to volatile materials responsible for the fragrance of plants. The manifold aspects of these materials have ' . they sat down to eat bread: and they been studied by chemists, plant physiologists, and lifted up their eyes and looked, and behold, a pharmacologists as well as historians. company of Ishmaelites came from Gilead with One could write a world history on the basis of their camels bearing spicery and balm and myrrh, essential oils. These highly valued products have going to carry it down to Egypt." played a very important role in the economy of many countries - especially in classical times. Often the fragrant oils were endowed with myster- In the ancient countries of the Orient, in Greece, ious properties and it is said that Helen of Troy and in Rome the essence of flowers and roots was possessed a secret perfume, revealed to her by Venus, extracted by placing them in fatty oils. The glass which was responsible for her fabulous beauty. While les containing these mixtures were warmed in the the secret of such magic perfumes has been lost, later , and finally the odoriferous oils were separated generations tried to make zip for this in quantity. from the solid materials. Sometimes the flowers or Laws were even passed in England during the reign plants were macerated with wine, and the product ob- of King George 111, in 1774, which forbade women tained by digestion was then filtered and boiled to to "seduce and betray into matrimony any of His a syrup. Majesty's subjects by the use of scents, cosmetics and These fatty oils and syrups containing the fragrance other artificial means." Penalties were the same as of flowers and leaves and the oleoresin of trees - those used against witchcraft and upon conviction such as labdanum, myrrh, and incense - were some the marriage would be null and void. nets of commerce in ancient Our present Federal Food and Drug Administration may not go quite so far. It has stated repeatedly Relics of the Egyptian period, several thousand that it does not believe in the cure-all properties of years ago, show evidence of the use of these products. fragrant oils, nor in the radio and television claims of Even the one-room exhibit of Egyptian art in the irresistible effects of perfumes and ointments on males L.A. County Museum contains many items relating and females. Everyone can readily agree, however, to the abundant use of odoriferous oils and ointments that the fragrance of flower oils is pleasant, and the in daily life, and in religions ceremonies. The empty industry is hardly to blame if it has supplied us with mummy case in the corner of the Egyptian room has an abundance of the volatile odoriferous products. in the bottom of the ease a life-size painting of the Today, as thousands of years ago, natural as well as deceased which shows an oil jar at his right contain- artificial scents accompany us from early morning to ing odoriferous oil. The mummy itself was preserved late at night. with cedar oil and other resins such as myrrh and These odors take many forms. The eucalyptus trees cinnamon. in the center of the Caltech campus give off the odor In the Bible (Exodus 30:63 and 64) we find some of a well-known brand of cough drops. On the other detailed recipes for the preparation of an ointment hand, the eucalyptus at the entrance to the Athe- with which the altar, its vessels, candlesticks, and naeum smells quite different and resembles lemon; in even the priest, should be anointed. The exact com- fact it has been called E. ciiriodora, in distinction to 8 Engineering and Science Distillation in the 16th century: "In fire the juice of all bodies, bg means of art, becomes a vigorous liquid." the more common E. globulus. held in a wooden frame and stacked one 011 top of Each plant has its peculiar odor, and this odor is the other so that the flowers are surrounded by fat. most frequently the property of the oils secreted in While the odors are given off by the flowers they special cells, or in intercellular spaces in the plant. dissolve in the fat and afterwards the fat is collected These oil-filled spaces can readily be observed in an and extracted with alcohol. In this way the perfume orange peel. By bending the peel, the cell walls of industry obtains the highly valued and very expensive the container are torn and the droplets of orange oil absolutes of enfleurage. form a spray, which can be seen by the light of a This process doesn't fit too well into our present candle. The simple process of release of the oil by day economy and is gradually being replaced by sol- pressing is the basis of a large industry producing vent extraction with low-boiling petroleum fractions. orange and lemon oil in the nearby towns of Ontario The oils obtained by pressing oranges or lemons, or and Corona. those obtained by fat extraction, are volatile by them- The old way of producing this oil was to press by selves, or they can be distilled over with steam. hand and collect the oil in a sponge. When the sponge In areas far from civilization these distillations was saturated, the oil was squeezed out. This process are carried out in very much the same way that was is still used in Italy and Spain. An operator can col- described in the books on distillation printed in the lect from one to two pounds of oil per day from 200 16th century. pounds of fruit. In essential oil centers, on the other hand, we find Our California lemon and orange byproducts in- the most modern stills, capable of handling large dustry solves this problem by mechanically reproduc- quantities of oil. American oil of turpentine is pro- ing the work of the individual hand presser, In this duced in this way in Georgia and Florida by steam way the orange byproducts plant in Ontario supplies distilling of the oleoresins from the pine trees. When 400,000 pounds of orange oil per year. The lemon in- the mixture of water vapor and the volatile material dustry in Corona produces 650,000 pounds of lemon is condensed, two layers are formed. The top layer, oil per year. above the water, is an oily liquid, which is the tur- The oils so obtained are practically insoluble in pentine. What remains in the distilling flask is rosin. water, just like fatty oils; however, unlike these, they In this country 300,000 barrels of turpentine are pro- are volatile. A drop of volatile oil on filter paper dis- cessed every year ( with 50 gallons in each barrel). appears after a time, while a fat gives a lasting spot. The same process is used in the preparation of oil Turpentine can be used to remove the fat spot. This of peppermint.

Load more